Future<String> getData() {
  return Future.delayed(Duration(seconds: 2), () {
    return '当前时间：${DateTime.now()}';
  });
}

main() {
  Stream.fromFuture(getData())
    .listen((event) {print('Stream.fromFuture : $event');})
    .onDone(() {print('Stream.fromFuture done');});
}